Liquid optics image stabilization

ABSTRACT

A lens system suitable for use with a camera is disclosed. The lens system employs liquid optics to provide stabilization of an image. A pair of liquid lens cells provides stabilization of the image. A second pair of liquid lens cells may provide stabilization in another direction. The two pairs of liquid cells may provide stabilization in any direction.

RELATED APPLICATIONS

This application is related to, and claims the benefit of U.S.Provisional 60/992,284 filed Dec. 4, 2007, the entirety of which ishereby incorporated by reference herein and made a part of the presentspecification.

BACKGROUND

1. Field of the Invention

This invention relates to an optical lens system employing liquid opticsto stabilize an image.

2. Description of the Related Art

Optical image stabilization varies an optical path in a lens tostabilize an image reaching a sensor. For example, a floating lenselement may be moved orthogonally to the optical axis of the lens.Alternatively, mechanical image stabilization moves the sensor capturingthe image to counteract the motion of the camera. However, these imagestabilization devices rely upon mechanical movement of lens elements orsensors.

SUMMARY

Liquid lens cells can modify an optical path without relying uponmechanical movement of the liquid cell, thereby providing vibrationcompensation to stabilize an image. A liquid lens cell can be used withother lens elements aligned along at least two optical axes.

In one embodiment, the liquid lens cell comprises first and secondcontacting liquids, wherein a contacting optical surface between thecontacting liquids has a variable shape that is substantiallysymmetrical to its own optical axis and is asymmetrical to at least oneother optical axis. A plurality of lens elements and the liquid lenscell are configured to collect radiation emanating from an object sidespace and provide at least partial stabilization of radiation deliveredto an image side space.

Two or more liquid lens cells may be configured to provide furtherstabilization of radiation delivered to an image side space. Forexample, two liquid lens cells may be used to stabilize an image in asingle linear direction. The stabilization may correct, for example,horizontal or vertical jitter.

In another embodiment, four or more liquid lens cells are configured toprovide stabilization of radiation delivered to an image side space. Twoof the liquid lens cells may provide stabilization in one direction,while another two liquid lens cells provide stabilization in anotherdirection. The four or more liquid lens cells can together providestabilization in any direction.

A liquid lens cell comprising first and second contacting liquids may beconfigured so that a contacting optical surface between the contactingliquids has a variable shape that is substantially symmetrical relativeto an optical axis of the liquid lens cell. A plurality of lens elementscould be aligned along a common optical axis and arranged to collectradiation emanating from an object side space and delivered to an imageside space. The liquid lens cell could be inserted into an optical pathformed by the plurality of lens elements that are aligned along thecommon optical axis. The optical axis of the liquid lens cell could beparallel to the common optical axis, or it could be at an angle to thecommon optical axis.

An electronic control system may be used to control the variable shapeof the contacting optical surface in a liquid lens cell. Anaccelerometer, laser gyroscope, or the like may be used to detectmovement of one or more lens elements, and the shape of the contactingoptical surface may then be varied to compensate for the movement of thelens elements in order to stabilize the image.

The control system may be configured to detect panning of the camera, sothat the image shift due to the panning is not corrected. The controlsystem may also be configured to compensate for various types ofmovement. For example, the control system may compensate for vibrationhaving a frequency greater than 2 Hz.

A first liquid lens cell and a second liquid lens cell may be controlledin tandem to provide stabilization in at least one direction forradiation delivered to an image side space. The power of the firstliquid lens cell may be substantially equal and opposite a power of thesecond liquid lens cell so that focus at an image plane is axiallyfixed. The power of the first liquid lens cell and a power of the secondliquid lens cell may be set to provide focus at an image plane.

In one embodiment, a first pair of liquid lens cells are offset fromeach in one direction, and a second pair of liquid lens cells offsetfrom each in a direction substantially perpendicular to the firstdirection. The first pair of liquid lens cells provide imagestabilization in the direction of the offset of the first pair, and thesecond pair of liquid lens cells provide image stabilization in thedirection of the offset of the second pair.

A first pair of liquid lens cells may be offset from each other in onedirection, and a second pair of liquid lens cells may be offset fromeach other in a substantially different direction, with the magnitude ofthe offset of the second pair of liquid lens cells being greater orlesser than the magnitude of the offset of the first pair of liquid lenscells. For example, a stabilization range for the first pair of liquidlens cells may be greater than twice a stabilization range for thesecond pair of liquid lens cells.

In any of these embodiments, one or more additional liquid lens cellscould be used to compensate for thermal effects, adjust the focus ofradiation delivered to an image side space or as part of a zoomconfiguration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a camera.

FIG. 2 is an optical diagram of a zoom lens system employing liquids.

FIGS. 3A and 3B are optical diagrams of the liquid cell of the zoom lenssystem of FIG. 2 showing the surface shape between the liquids.

FIGS. 4A, 4B and 4C are optical diagrams of the zoom lens system of FIG.2 illustrating different positions of the zoom lens groups and surfaceshapes between the liquids to produce different focal lengths and focusdistances.

FIGS. 5A, 5B and 5C are modulation transfer function performancediagrams of the zoom lens system of FIGS. 4A, 4B and 4C.

FIGS. 6A and 6B are optical diagrams of a lens system employing liquidsto stabilize an image in one direction.

FIGS. 7A and 7B are optical diagrams of a lens system employing liquidsto stabilize an image in any direction.

FIGS. 8A, 8B and 8C are optical diagrams of the lens system of FIGS. 7Aand 7B illustrating different positions of the zoom lens groups andsurface shapes between the liquids to produce different focal lengthsand focus distances.

FIGS. 9A, 9B, 9C and 9D are optical diagrams of the lens system of FIGS.7A and 7B illustrating different positions of the zoom lens groups andsurface shapes between the liquids to stabilize an image.

FIGS. 10A, 10B, 10C and 10D are optical diagrams of the lens system ofFIGS. 7A and 7B illustrating different positions of the zoom lens groupsand surface shapes between the liquids to stabilize an image.

FIGS. 11A, 11B and 11C are modulation transfer function performancediagrams of the lens system as configured in FIGS. 8A, 8B and 8C.

FIGS. 12A, 12B, 12C and 12D are modulation transfer function performancediagrams of the lens system as configured in FIGS. 9A, 9B, 9C and 9D.

FIGS. 13A, 13B, 13C and 13D are modulation transfer function performancediagrams of the lens system as configured in FIGS. 10A, 10B, 10C and10D.

DETAILED DESCRIPTION

In the following description of preferred embodiments, reference is madeto the accompanying drawings that form a part hereof, and in which isshown by way of illustration specific embodiments in which the inventionmay be practiced. It is to be understood that other embodiments may beutilized and structural changes may be made without departing from thescope of the invention.

U.S. Provisional Patent Application No. 60/783,338 filed on Oct. 8, 2007and titled “Liquid Optics Zoom Lens and Imaging Apparatus,” hereinincorporated by reference in its entirety, discloses a zoom lens systemthat employs liquid optics to provide zoom and focus functionality.Liquid optics may also be used to provide stabilization. Exemplaryembodiments using liquid optics are disclosed herein.

Liquid Optics in a Zoom Lens System

FIG. 1 illustrates a block diagram of a camera 100 with a zoom lens 102.A zoom lens is an assembly of lens elements with the ability to varyfocal length. The individual lens elements may be fixed in place, orslide axially along the body of the lens. A lens group may consist ofone or more lens elements. At least one movable lens group providesvariation of the magnification of an object. As the at least one lensgroup moves to accomplish magnification, the position of the focal planemay also move. At least one other movable lens group may move tocompensate for the movement of the focal plane to maintain a constantfocal plane position. Compensation for the movement of the focal planemay also be achieved mechanically by moving the complete lens assemblyas the magnification of the lens changes.

The individual lens elements may be constructed from solid-phasematerials, such as glass, plastic, crystalline, or semiconductormaterials, or they may be constructed using liquid or gaseous materialssuch as water or oil. The space between lens elements could contain oneor more gases. For example normal air, nitrogen or helium could be used.Alternatively the space between the lens elements could be a vacuum.When “Air” is used in this disclosure, it is to be understood that it isused in a broad sense and may include one or more gases, or a vacuum.

A zoom lens will often have three or more moving lens groups to achievethe zoom and focusing functions. A mechanical cam may link two movablelens groups to perform zooming, and a third movable lens group may beused for focus.

The zoom range is determined in part by the range of movement for themovable lens elements. Greater zoom ranges require additional space formovement of the lens elements. One or more of the movable lens groupsmay be replaced by a lens group that implements liquid cell technology.Because liquid cells do not require space for axial movement, the lengthof the lens design which contains the movable lens groups may bereduced. Alternatively, the space that would have been used for axialmovement of the movable lens groups can be used to include additionaloptical elements or folds. Although a liquid cell does not require spacefor movement, it may be part of a movable lens group.

A liquid cell may be used for both zooming and focusing. In oneembodiment, a movable lens group is used with a lens group thatimplements liquid cell technology. There is no need for a mechanical camwith one movable lens group. Not having a cam allows for additionalmovements.

One or more movable lens groups are used with one or more liquid cellsto achieve zooming and focusing. A single movable lens group and asingle liquid cell can perform both zooming, focusing and compensationfor thermal effects. In one implementation, a zoom system has at least afirst and second lens group. The first lens group is relatively highpower, and the second lens group is relatively low power, the lens powerbeing equivalent to the inverse of the focal length of the lens. Thefirst lens group comprises conventional glass or other solid lenses andthe second lens group comprises at least one liquid lens.

A liquid cell uses two or more liquids to form a lens. The focal lengthof the lens is partly determined by the angle of contact between theliquids and the difference in the refractive index of the liquids. Therange of power variation is limited by the difference in the refractiveindex of the liquids employed and the finite range of radius ofcurvature at the surface interface between the liquids due to spaceconstraints. U.S. Patent Application Publication No. 2006/0126190,herein incorporated by reference, discloses a lens employing thedeformation of a drop of liquid through electrowetting. U.S. Pat. No.6,936,809, herein incorporated by reference, discloses usingelectrowetting technology to shift laterally an image formed on an imageplane.

Presently contemplated liquid lens systems will have a difference inrefractive index of at least about 0.2, preferably at least about 0.3,and in some embodiments at least about 0.4. Water has a refractive indexof about 1.3, and adding salt may allow varying the refractive index toabout 1.48. Suitable optical oils may have a refractive index of atleast about 1.5. Even by utilizing liquids with higher, lower or higherand lower refractive indices, for example a higher refractive index oil,the range of power variation remains limited. This limited range ofpower variation usually provides less magnification change than that ofa movable lens group. Therefore, in a simple zoom lens system, toprovide zooming while maintaining a constant image plane position mostof the magnification change may be provided by one movable lens groupand most of the compensation of defocus at the image plane during themagnification change may be provided by one liquid cell. However, itshould be noted that more movable lens groups or more liquid cells, orboth, may be utilized.

The movable lens group can have a positive or negative power. The liquidcell can have a range of variable power where the power is alwayspositive, always negative or goes from positive to negative, or viceversa. Proper arrangement of the movable lens group and the liquid cellprovides an extended zoom ratio of greater than 2× and preferablygreater than 3× while offering good image quality throughout the zoomrange. The arrangement, in addition to zooming, may also providefocusing at different object distances over an extended focus range byutilizing additional available power variation from the liquid cell, themovable lens group or both. This additional power variation provided bythe liquid cell or the movable lens group or both for focusing isreadily available. Since one movable lens group does not necessarilyrequire a cam with a fixed locus of movement, the position of themovable zoom lens group can be adjusted for zooming and focusing. Highperformance imaging is achieved by utilizing both the movable zoom lensgroup and the liquid cell for zooming and focusing.

It is also possible to replace the movable zoom lens group with at leastone liquid cell. This would increase the complexity of the opticalsystem and may cause the optical system to have other disadvantages,such as reduced magnification change.

FIG. 1 also illustrates a lens control module 104 that controls themovement and operation of the lens groups in lens 102. The controlmodule 104 includes electronic circuitry that controls the radius ofcurvature in the liquid lens cell. Electronic circuitry may also controlthe position of the movable lens group. The appropriate electronicsignal levels for various focus positions and zoom positions can bedetermined in advance and placed in a lookup table. Alternatively,analog circuitry or a combination of circuitry and a lookup table cangenerate the appropriate signal levels. In one embodiment, a polynomialis used to determine the appropriate electronic signal levels. Pointsalong the polynomial could be stored in a lookup table or the polynomialcould be implemented with circuitry.

Thermal effects may also be considered in the control of the radius ofcurvature of surface between the liquids or the position of movable lensgroups or both. The polynomial or lookup table may include an additionalvariable related to the thermal effects.

The control module 104 may include preset controls for specific zoomsettings or focal lengths. These settings may be stored by the user orcamera manufacturer.

FIG. 1 further illustrates an image capture module 106 that receives anoptical image corresponding to an external object. The image istransmitted along an optical axis through the lens 102 to the imagecapture module 106. The image capture module 106 may use a variety offormats, such as film (e.g., film stock or still picture film), orelectronic image detection technology (e.g., a CCD array, CMOS device orvideo pickup circuit). The optical axis may be linear, or it may includefolds.

Image storage module 108 maintains the captured image in, for example,on-board memory or on film, tape or disk. In one embodiment, the storagemedium is removable (e.g., flash memory, film canister, tape cartridgeor disk).

Image transfer module 110 provides transferring of the captured image toother devices. For example, the image transfer module 110 may use one ora variety of connections such as a USB port, IEEE 1394 multimediaconnection, Ethernet port, Bluetooth wireless connection, IEEE 802.11wireless connection, video component connection, or S-Video connection.

The camera 100 may be implemented in a variety of ways, such as a videocamera, a cell phone camera, a digital photographic camera, or a filmcamera.

An embodiment of a zoom lens will now be described by way of a designexample. Referring first to FIG. 2, each lens element is identified bythe letter “E” followed by a numeral from 1 through 20 and the generalconfiguration of each lens element is depicted, but the actual radius ofeach lens surface is set forth below in TABLE 1. The lens, object, stopor iris and image surfaces are identified by a numeral from 1 through36. The three lens groups are identified in FIG. 2 by the letter “G”followed by a numeral from 1 through 3 and the liquid lens cell isidentified by the letters “LC” and comprises optical surfaces 19 through23. The optical axis is identified in FIG. 2 by a numeral 38.

Each lens element has its opposite surfaces identified by a separate butconsecutive surface number as, for example, lens element E1 has lenssurfaces 2 and 3, lens element E9 has lens surfaces 17 and 18 and soforth, as shown in FIG. 2. The location of the object to be imaged,particularly as it relates to focus distance, is identified by avertical line and the numeral 1 on the optical axis 38 and the realimage surface is identified by the numeral 36. All of the lens surfacesare spherical or plano except lens surfaces 4 and 8 which are asphericsurfaces that are non-spherical, non-plano but rotationally symmetricalabout the optical axis.

Before describing the detailed characteristics of the lens elements, abroad description of the lens groups and their axial positions andmovement, and, the liquid lens cell and the variation in surface shapeof contacting liquids will be given for the zoom lens system 60.

The positive or negative power of each lens group is defined as theinverse of the focal length. The resultant optical power of each groupof lenses is as follows: the objective lens group G1 is positive, thezoom lens group G2 is negative and the rear lens group G3 is positive,from a lower positive value to a higher positive value as the shape ofthe surface in the liquid cell is varied. The horizontal arrow witharrowheads on both ends in the upper portion of FIG. 2 indicates thatthe zoom lens group G2 is movable in both axial directions.

While only the lens elements are physically shown in FIG. 2, it is to beunderstood that mechanical devices and mechanisms are provided forsupporting the lens elements and for causing axial movement of themovable zoom lens group in a lens housing or barrel. In addition, it isto be understood that electronic circuitry changes the profile of thevariably shaped optical surface in the liquid lens cell.

The lens construction and fabrication data for the above described zoomlens system 60 is set forth below in TABLE 1. The data in TABLE 1 isgiven at a temperature of 25° C. (77° F.) and standard atmosphericpressure (760 mm Hg). Throughout this specification measurements are inmillimeters (mm) with the exception of wavelengths which are innanometers (nm). In TABLE 1, the first column “Item” identifies eachoptical element and each location, i.e. object plane, image plane, etc.,with the same numeral or label as used in FIG. 2. The second columnidentifies the “Group” to which that optical element (lens) belongs withthe same numerals used in FIG. 2. The third column “Surface” is a listof the surface numbers of the object (line “1” in FIG. 2 and “Object” inTABLE 1), the Stop (iris) 13 and each of the actual surfaces of thelenses, as identified in FIG. 2. The fourth column “Focus Position”identifies three typical focus positions (F1, F2 and F3) for the zoomlens system 60 wherein there are changes in the distance (separation)between some of the surfaces listed in the third column and there arechanges in the radius of curvature of the surface 21 listed in the thirdcolumn, as described below more thoroughly. The fifth column“Separation” is the axial distance between that surface (third column)and the next surface. For example, the distance between surface S2 andsurface S3 is 1.725 mm.

The sixth column, headed by the legend “Radius of Curvature,” is a listof the optical surface radius of curvature for each surface, with aminus sign (−) meaning the center of the radius of curvature is to theleft of the surface, as viewed in FIG. 2 and “Infinity” meaning anoptically flat surface. The asterisk (*) for surfaces 4 and 8 indicatethese are aspheric surfaces for which the “radius of curvature” is abase radius. Use of aspherical surfaces provides for the correction ofaberrations in the zoom lens while enabling a smaller overall size and asimpler configuration. The formula and coefficients for the surfaceprofiles of aspheric surfaces 4 and 8 are governed by the followingequation:

$z = {\frac{{cy}^{2}}{1 + \left\lbrack {1 - {\left( {1 + \kappa} \right)c^{2}y^{2}}} \right\rbrack^{1/2}} + {Ay}^{4} + {By}^{6} + {Cy}^{8} + {Dy}^{10} + {Ey}^{12} + {Fy}^{14}}$

-   -   where:    -   c=surface curvature (c=1/r where r is the radius of curvature)    -   y=radial aperture height of surface measured from the X and Y        axis, where:

y=(X ² +Y ²)^(1/2)

-   -   κ=conic coefficient    -   A, B, C, D, E, F=4^(th), 6^(th), 8^(th), 10^(th), 12^(th) and        14^(th), respectively, order deformation coefficients    -   z=position of a surface profile for a given y value or measured        along the optical axis from the pole (i.e., axial vertex) of the        surface        The coefficients for surface 4 are:

κ=−0.6372

A=+0.9038×10⁻⁶

B=+0.2657×10⁻⁸

C=−0.1105×10⁻¹⁰

D=+0.4301×10⁻¹³

E=−0.8236×10⁻¹⁶

F=+0.6368×10⁻¹⁹

The coefficients for surface 8 are:

κ=+0.0000

A=+0.5886×10⁻⁴

B=−0.5899×10⁻⁶

C=+0.8635×10⁻⁸

D=−0.5189×10⁻¹⁰

E=−0.1186×10⁻¹¹

F=+0.1631×10⁻¹³

Columns seven through nine of TABLE 1 relate to the “Material” betweenthat surface (third column) and the next surface to the right in FIG. 2,with the column “Type” indicating whether there is a lens (Glass) orempty space (Air) or liquid lens (Liquid) between those two surfaces.The glass and liquid lenses are identified by optical glass or liquid inthe column “Code”. For convenience, all of the lens glass has beenselected from glass available from Ohara Corporation and the column“Name” lists the Ohara identification for each glass type, but it is tobe understood that any equivalent, similar or adequate glass may beused. Also, the lens liquid of oil has been selected from a liquidavailable from Cargille Laboratories, Inc., and water is commonlyavailable from various sources, but it is to be understood that anyequivalent, similar or adequate liquid may be used. The water liquid atsurface 20 has the following refractive indices 1.331152, 1.332987,1.334468 and 1.337129 at respective wavelengths 656.27, 589.29, 546.07and 486.13 nanometers. The oil liquid at surface 21 has the followingrefractive indices 1.511501, 1.515000, 1.518002 and 1.523796 atrespective wavelengths 656.27, 589.29, 546.07 and 486.13 nanometers.

The last column of TABLE 1 headed “Aperture Diameter” provides themaximum diameter for each surface through which the light rays pass. Allof the maximum aperture diameters, except for the Stop surface 13, aregiven at a wavelength of 546.1 nanometers for a maximum image diameterof about 6 mm and F-numbers of F/2.8 to F/4.0 at the Image Plane, forall Zoom and Focus Positions. The maximum aperture diameter of the Stopsurface 13 is given in TABLE 1 at a wavelength of 546.1 nanometers andan F-number of F/2.8 at the Image Plane for Zoom Position Z1 and FocusPosition F1. At the Image Plane 36, the Maximum Aperture Diameter isgiven as an approximate value.

TABLE 1 Optical Prescription Focus Radius of Material Aperture ItemGroup Surface Position Separation Curvature (mm) Type Name Code Diameter(mm) Object 1 F1 Infinity Infinity Air F2 1016.2500 F3 378.7500 E1 G1 2All 1.7250 59.1716 Glass SLAM66 801350 37.161 3 All 0.0750 34.5954 Air35.567 E2 G1 4 All 6.7565 *33.0488 Glass SFPL51 497816 35.618 5 All0.0750 2758.9929 Air 35.182 E3 G1 6 All 5.8657 32.7151 Glass SFPL53439950 33.680 7 F1 TABLE 2 −2981.4301 Air 33.034 F2 TABLE 2 F3 TABLE 2E4 G2 8 All 0.7652 *461.6464 Glass SLAH64 788474 14.273 9 All 3.83338.3339 Air 11.605 E5 G2 10 All 2.6582 −12.6370 Glass SFPL53 43995011.587 E6 G2 11 All 3.2165 18.1883 Glass SLAM66 801350 12.383 12 F1TABLE 3 −55.4718 Air 12.337 F2 TABLE 3 F3 TABLE 3 Stop/ G3 13 All 0.6371Infinity 6.708 Iris E7 G3 14 All 5.7168 −26.3844 Glass SLAH65 8044666.757 E8 G3 15 All 2.6250 9.3177 Glass STIH53 847238 8.304 16 All 0.8432−16.3366 Air 8.533 E9 G3 17 All 2.5647 −9.2859 Glass SLAH58 883408 8.50818 All 2.2767 −11.1961 Air 9.665 E10 G3 19 All 0.4500 Infinity GlassSBSL7 516641 10.151 E11 G3 20 All 1.5000 Infinity Liquid WATER 10.201E12 G3 21 F1 1.5000 TABLE 4 Liquid OIL T30004091- 10.367 F2 TABLE 4 ABF3 TABLE 4 E13 G3 22 All 0.4500 Infinity Glass SBSL7 516641 10.584 23All 0.0750 Infinity Air 10.642 E14 G3 24 All 3.1583 120.2680 GlassSLAH65 804466 10.680 E15 G3 25 All 0.6000 −7.2241 Glass STIH10 72828510.724 26 All 0.0750 13.8153 Air 10.634 E16 G3 27 All 3.0844 13.7118Glass SBSM10 623570 10.696 28 All 0.3424 −11.1618 Air 10.713 E17 G3 29All 0.6000 −9.5071 Glass STIH13 741278 10.652 30 All 0.0750 68.8748 Air11.180 E18 G3 31 All 1.7063 18.2078 Glass SLAL13 694532 11.589 32 All26.6908 −115.6915 Air 11.592 E19 G3 33 All 3.1085 10.2784 Glass SNPH1808228 9.888 E20 G3 34 All 2.7193 −9.9003 Glass SLAH58 883408 9.581 35All 2.6192 58.0014 Air 7.805 Image 36 All 0.0000 Infinity Air 6.008

Zoom lens system 60 is provided with an optical stop at the surface 13which controls the diameter of the aperture through which light rays maypass at that point. The optical stop is the location at which a physicaliris (or diaphragm) is located. The iris is located before the rear lensgroup G3 and is axially stationary with that lens group. Note that inFIG. 4A, the rim rays pass through the axis side of the tic marks of theoptical stop surface 13 such that the zoom lens system has no vignettingof light beams at any field position, zoom position and focus position.However, note that the F-number varies through zoom and focus positionsand the iris opens or closes accordingly. The diameter of the iris atzoom positions Z1-Z8 for focus position F1 is 6.71, 6.39, 5.96, 5.53,5.18, 4.84, 4.63 and 4.61. This shows that the iris located at 13 shouldclose as the focal length increases. As compared to focus position F1,the diameter of the iris at zoom positions Z1-Z8 for focus positions F2and F3 changes by a small amount of less than 0.3 mm diameter tomaintain the same F-numbers as for focus position F1.

Referring to TABLE 1, for illustrating the scope and versatility of thedesign there are eight different Zoom Positions Z1, Z2, Z3, Z4, Z5, Z6,Z7 and Z8 and three different Focus Positions F1, F2 and F3 set forth inthe data which, in effect, provides specific data for twenty four(8×3=24) different combinations of positions for the movable zoom lensgroup G2 and the variable shape optical surface 21.

The focal lengths of zoom lens system 60 for zoom positions Z1-Z8 atfocus position F1, at a wavelength of 546.1 nanometers are; 5.89, 7.50,11.25, 15.00, 18.75, 30.00, 41.25 and 45.00 mm, respectively. Thecorresponding F-numbers for the focal lengths for data positions Z1-Z8,at a wavelength of 546.1 nanometers are; 2.80, 2.90, 3.05, 3.25, 3.45,3.70, 3.95 and 4.00, respectively.

For Focus Position F1 the Object Plane 1 is assumed to be at infinity,for F2 the Object Plane 1 is at an intermediate distance of about1016.25 mm, and for F3 the Object Plane 1 is at a close distance ofabout 378.75 mm (i.e., 378.75 mm away from the image plane). At each ofthese three Focus Positions F1, F2 and F3, the lens groups G1 and G3remain in the same position throughout the full range of movement of thezoom lens group G2. TABLES 2 and 3 provide separation values of surfaces7 and 12 and TABLE 4 provides the radii of curvature of surface 21 forzoom positions Z1-Z8 and F1-F3.

TABLE 2 Separation Values for Surface 7 Surface Focus Z1 Z2 Z3 Z4 Z5 Z6Z7 Z8 7 F1 0.0832 5.7132 13.7126 18.4633 21.6974 27.4007 30.5400 31.30967 F2 0.0902 5.7486 13.6468 18.3289 21.5154 27.0776 30.0174 30.7361 7 F30.0750 5.6942 13.4674 18.1217 21.3355 26.7467 29.5798 30.2701

TABLE 3 Separation Values for Surface 12 Surface Focus Z1 Z2 Z3 Z4 Z5 Z6Z7 Z8 12 F1 31.5294 25.8992 17.8996 13.1486 9.9140 4.2101 1.0701 0.300012 F2 31.5178 25.8581 17.9590 13.2762 10.0892 4.5268 1.5870 0.8729 12 F331.5324 25.9120 18.1380 13.4831 10.2689 4.8577 2.0248 1.3384

TABLE 4 Radii of Curvature for Surface 21 Surface Focus Z1 Z2 Z3 Z4 Z5Z6 Z7 Z8 21 F1 −33.9902 −40.9700 −60.9667 −84.8892 −106.7630 −101.7297−58.3998 −48.6792 21 F2 −34.3890 −42.0587 −65.5384 −101.1799 −154.9184−370.2777 −263.5374 −212.3139 21 F3 −35.0134 −43.6001 −72.6330 −133.7178−351.2333 214.4454 125.5481 115.8049

It will be understood that continuous focusing is available between theextreme Focus Positions F1 and F3, that continuous zooming is availablebetween the extreme Zoom Positions Z1 and Z8, and that any combinationof continuous focusing and zooming is available within the describedfocus and zoom ranges with the lens system 60.

The zoom lens system 60 shown in FIG. 2 and prescribed in TABLE 1 hasfocal lengths for lens groups G1 and G2 of 54.30 and −12.25 mmrespectively. Also, lens group G3, due to the variable shape of theoptical surface 21 between the liquids, has a variable focal lengthwhich has a minimum value of +30.18 mm and a maximum value of +38.97 mmat zoom position Z1 and focus position F1, and, zoom position Z8 andfocus position F3 respectively. The liquid cell LC of zoom lens system60 is shown in FIGS. 3A and 3B, demonstrating the two extreme radii ofcurvature from TABLE 1 of the variable shape optical surface 21 betweenthe liquids. In FIGS. 3A and 3B the two radii of curvature of surface 21are about −33.99 and +115.80 mm respectively. The two extreme focallengths of the liquid cell LC, in FIGS. 3A and 3B, are −185.20 and630.97 mm respectively. This difference happens at zoom position Z1 andfocus position F1, and, zoom position Z8 and focus position F3. In thisembodiment the volume of the two liquids between surfaces 20, 21 and 21,22 varies as the shape of the variable surface changes. However, it isalso possible to maintain a constant volume for each liquid by applyingsmall, equal but opposite, changes to the axial separation betweensurfaces 20, 21 and 21, 22.

Referring now to FIGS. 4A, 4B, and 4C, the zoom lens system 60 is shownwith the zoom lens group in various positions, the shape of the variablesurface in the liquid cell in various positions and with light raytraces for those positions. FIG. 4A represents the focus position F1 andzoom position Z1 for which data is set forth above in TABLE 1 withinfinity focus and a small focal length of about 5.9 mm. FIG. 4Brepresents the focus position F2 and zoom position Z3 from TABLE 1 withan intermediate focus and a focal length of about 11.3 mm. FIG. 4Crepresents the focus position F3 and zoom position Z8 from TABLE 1 withclose focus and a focal length of about 44.8 mm.

FIGS. 4A, 4B and 4C show three axial locations of the zoom lens group G2with corresponding three surface shapes for the variable optical surface21 for the respective zoom and focus positions; Z1, F1 and Z3, F2 andZ8, F3.

The optical performance of zoom lens system 60 is given in FIGS. 5A, 5Band 5C wherein the diffraction based polychromatic modulation transferfunction (“MTF”) data (modulation versus spatial frequency) is shown inpercent (%) for five different Field Positions in three differentcombinations of the zoom and focus positions set forth in TABLE 1,namely (Z1, F1), (Z3, F2) and (Z8, F3) which are representativeexamples. The Field Positions are set forth in two values, both thenormalized image height (mm) and the actual object space angle (degree)from the optical axis. The MTF percentages are at the wavelengths andweightings set forth in the top right-hand corner of FIGS. 5A, 5B and 5Cand are graphically shown for tangential (T) and radial (R) directionsof measurement at the image plane 36. Note that the tangential andradial values are equal at the axial field position (AXIS) and aredepicted with only one plot. The maximum spatial frequency shown is 90cycles/mm which given the image diameter of about 6 mm and choice ofdetector pixel size may provide high quality images at least up to highdefinition television (HDTV) resolution, namely 1920 pixels horizontallyby 1080 pixels vertically. MTF at a spatial frequency is a relativelystandard measurement of optical performance, wherein the value “90cycles/mm” means 90 pairs of black and white lines per millimeter on achart from which the clarity is determined. The highest MTF value isabout 89% at the full radial field for zoom position Z1 and focusposition F2. The lowest MTF value is about 58% at the full tangentialfield for zoom position Z8 and focus position F3. The minimum relativeillumination is about 75% at zoom position Z1 and focus position F1. Ingeneral, higher relative illumination values are better, because a lownumber means that light is falling off in the corners of the picture.High full field relative illumination is preferred for state of the artdetectors, which have a constant response to light in all areas and willfaithfully reproduce shading in the corners of the image along withchanges to the image during zooming. Illumination less than 50% mayresult in shading in an electronic detector, but will likely beacceptable for film. The highest positive distortion is +3.04% at zoomposition Z3 and focus position F1 and the lowest negative distortion is−2.98% at zoom position Z1 and focus position F3. The so-called“breathing” problem of lenses in general (but which may be moreprevalent in zoom lenses) wherein the image changes size from far toclose focus is virtually absent in zoom lens system 60 at the shortfocal length of the zoom range where it is most noticeable due to thelarge depth of field. The lowest breathing is −0.2% at zoom position Z1and focus position F3 and the highest breathing is −19.5% at zoomposition Z8 and focus position F3. Breathing is the percentage change inmaximum field angle from infinity focus to a selected focus.Accordingly, at infinity focus (F1), breathing is zero because that isthe reference field of view.

All of the performance data is given at a temperature of 25° C. (77°F.), standard atmospheric pressure (760 mm Hg), and at the fullapertures available in the zoom lens system 60. However, the zoom lenssystem 60 does provide substantially constant performance, as forexample the MTF values, over a temperature range of 0° to 40° C. (32° to104° F.) and, if a small degradation in performance (MTF) is acceptable,the operable temperature range can be extended to −10° to 50° C. (140 to122° F.) or more. For a change in temperature the optimum performancemay be achieved by further axial adjustment of the zoom lens group G2 orfurther change of shape of the contacting optical surface 21 or acombination of both together. This may happen at all zoom and focuspositions. At low temperatures of about 0° C. (32° F.) or below, toavoid freezing (forming a solid), the liquids may need to be heated orbe replaced with doped liquids in a similar way to anti-freeze beingadded to water in a car radiator for low temperature operation. However,note that these material temperature changes preferably should notsignificantly change the optical characteristics of the liquids.

While the described embodiment using zoom lens system 60 is of theappropriate dimensions for use with a 6 mm diameter (so called thirdinch chip sensor), the dimensions of this zoom lens system may beappropriately scaled up or down for use with various film and electronicdetector image formats.

Among the many advantages of the zoom lens system 60 is that ofproviding zooming over a wide range of focal lengths utilizing only oneaxially moving zoom lens group. The design of the zoom lens system 60creates a high performance and mechanically less complex lens systemthan most conventional high performance zoom lens systems which requireat least two axially movable zoom lens groups and correspondingmechanics. The unique lens design of the zoom lens system 60 providesfocusing over a large region of focus distance without additionalmovable lens groups and corresponding mechanics. The disclosed design ofzoom lens system 60 is exemplary, and other designs will fall within thescope of the invention. Other features and advantages of the zoom lenssystem 60 will appear to those skilled in the art from the foregoingdescription and the accompanying drawings.

Liquid Optics in a Lens System Employing Image Stabilization

FIGS. 6A and 6B show an optical diagram of a lens system employingliquids to stabilize an image, FIG. 6A shows the lens system in the YZplane, where the liquid lens cells 70 and 71 are off-axis, decentered,and slightly tilted along the Y axis. FIG. 6B shows the lens system inthe XZ plane, where the liquid lens cells 70 and 71 are centered alongthe X axis. In this simplified lens system, light passes from the objectspace through a lens element 72. On the other side of the iris, thelight passes through liquid lens cells 70 and 71. Lens element 73converges the light onto image plane 74.

The optical diagram in FIG. 6A illustrates the effects of tilting, orrotating, the lens in the YZ plane. As illustrated, tilting in the YZplane causes an image at the image plane 74 to shift up or down. Theliquid lens cells 70 and 71 are positioned so that they can becontrolled in tandem to compensate for the effects of tilting the lensin the YZ plane.

FIGS. 7A and 7B show an optical diagram of a lens system 80 employingfour liquid lens cells to stabilize an image. The lens system 80 may beused with a camera 100. FIG. 7A shows the lens system 80 in the YZplane, and FIG. 7B shows the lens system 80 in the XZ plane. The lenssystem 80 comprises a first stationary objective lens group 81, a secondmoving lens group 82, iris 83, a third stationary lens group 84, a firstliquid lens cell 85, a fourth stationary lens group 86, second to fifthliquid lens cells 87, 88, 89, 90 and a fifth stationary lens group 91.The image is formed on image plane 92. Liquid lens cells 87 and 88 areoffset in opposite directions along the y-axis, and liquid lens cells 89and 90 are offset in opposite directions along the x-axis. Accordingly,control of the variable surface shapes of liquid lens cells 87 and 88provides stabilization at the image plane 92 of the image along they-axis, and control of the variable surface shapes of liquid lens cells89 and 90 provides stabilization at the image plane 92 of the imagealong the x-axis.

The configuration illustrated in FIGS. 7A and 7B, shows the liquid lenscells as aligned along the z-axis. Alternatively, the liquid lens cellscould be tilted about the z-axis in addition to being offset along thex-axis or y-axis, or the liquid lens cells could be tilted about thez-axis without being offset along the x-axis and the y-axis. Offsettingthe liquid lens cells along the x-axis or y-axis or both increases thephysical diameter of the lens cells in system 80. Tilting the liquidlens cells may allow reduction or elimination of the offsets in the xand y directions which may reduce the physical diameter of the liquidlens cells, and may allow for a better image stabilization.

The optical power and focal lengths of each group of lenses which do notcontain liquid lens cells in FIGS. 7A and 7B is as follows: theobjective lens group 81 is positive and +54.700 mm, the moving lensgroup 82 is negative and −12.165 mm, the lens group 84 is positive and+70.285 mm, the lens group 86 is positive and +42.266 mm and the rearlens group 91 is positive and +19.147 mm.

TABLE 5 sets forth the general configuration of the lens elementsillustrated in FIGS. 7A and 7B. The data in TABLE 5 is given at atemperature of 25° C. (77° F.) and standard atmospheric pressure (760 mmHg). The focal length range is approximately 6 mm to 45 mm. The field ofview range is approximately 56.70 to 7.70 (including distortion atinfinity focus position F1). The zoom ration is approximately 7.5×(7.5:1). The image size is approximately Ø6 mm using a 16:9 format. Thefocus range is approximately infinity (focus position F1) to 378.25 mm(focus position F3) as measured from an object to the vertex of thenearest powered lens surface. The waveband range is approximately 486 nmto 656 nm. The lens system 80 provides image stabilization in the rangeof approximately ±¼ picture half height and ±⅛ picture half width fromat least about a focal length from 15 mm to 45 mm.

TABLE 5 Optical Prescription Radius of Aperture Focus SeparationCurvature Material Diameter/2 Group Item Surface Position (mm) (mm) TypeName Code (mm) 1 F1 Infinity Infinity Air F2 1016.2500 F3 378.7500 81 E12 All 1.7250 59.1203 Glass SLAM66 801350 20.488 81 3 All 0.0750 34.4944Air 19.360 81 E2 4 All 7.2445 *32.9559 Glass SFPL51 497816 19.362 81 5All 0.0750 −1679.0367 Air 19.149 81 E3 6 All 5.8060 32.1676 Glass SFPL53439950 17.393 81 7 F1 TABLE 6 603.6202 Air 17.043 F2 TABLE 6 F3 TABLE 682 E4 8 All 0.7652 *421.5729 Glass SLAH64 788474 7.306 82 9 All 4.00618.3253 Air 5.910 82 E5 10 All 2.6582 −12.7245 Glass SFPL53 439950 5.90082 E6 11 All 3.2165 18.4437 Glass SLAM66 801350 6.360 82 12 F1 TABLE 7−56.6544 Air 6.350 F2 TABLE 7 F3 TABLE 7 83 Iris/ 13 All 0.6371 InfinityAir TABLE 8 Stop 84 E7 14 4.3421 −26.4053 Glass SLAH65 804466 3.531 84E8 15 2.7592 10.8849 Glass STIH53 847238 4.471 84 16 1.9504 −19.6033 Air4.660 84 E9 17 3.4944 −10.0360 Glass SLAH58 883408 4.759 84 18 2.2880−12.3751 Air 5.698 85 E10 19 0.4500 Infinity Glass SBSL7 516641 6.036 85E11 20 1.5000 Infinity Liquid WATER 6.064 85 E12 21 F1 1.5000 TABLE 9Liquid OIL T30004091- 6.131 F2 TABLE 9 AB F3 TABLE 9 85 E13 22 0.4500Infinity Glass SBSL7 516641 6.305 85 23 0.0750 Infinity Air 6.343 86 E1424 5.5805 30.2458 Glass SLAH65 804466 6.443 86 E15 25 0.5250 −12.3375Glass STIH10 728285 6.358 86 26 0.0864 12.5297 Air 6.147 86 E16 273.0569 12.7154 Glass SBSM10 623570 6.175 86 28 0.2334 −17.0356 Air 6.17086 E17 29 0.5250 −15.0264 Glass STIH13 741278 6.148 86 30 0.0750 17.7536Air 6.261 86 E18 31 1.9042 17.3661 Glass SLAL13 694532 6.310 86 320.0750 −48.1100 Air 6.323 87 E19 33 0.6000 Infinity Glass SBSL7 5166419.837 87 E20 34 1.2011 Infinity Liquid WATER 9.823 87 E21 35 F1 3.1684TABLE 10 Liquid OIL T30004091- 9.777 F2 TABLE 10 AB F3 TABLE 10 87 E2236 0.6000 Infinity Glass SBSL7 516641 9.683 87 37 0.0750 Infinity Air9.662 88 E23 38 0.6000 Infinity Glass SBSL7 516641 9.691 88 E24 391.2011 Infinity Liquid WATER 9.676 88 E25 40 F1 3.1684 TABLE 11 LiquidOIL T30004091- 9.644 F2 TABLE 11 AB F3 TABLE 11 88 E26 41 0.6000Infinity Glass SBSL7 516641 9.570 88 42 0.0750 Infinity Air 9.549 89 E2743 0.6000 Infinity Glass SBSL7 516641 10.051 89 E28 44 1.2011 InfinityLiquid WATER 10.036 89 E29 45 F1 3.1684 TABLE 12 Liquid OIL T30004091-9.988 F2 TABLE 12 AB F3 TABLE 12 89 E30 46 0.6000 Infinity Glass SBSL7516641 9.893 89 47 0.0750 Infinity Air 9.869 90 E31 48 0.6000 InfinityGlass SBSL7 516641 9.901 90 E32 49 1.2011 Infinity Liquid WATER 9.885 90E33 50 F1 3.1684 TABLE 13 Liquid OIL T30004091- 9.830 F2 TABLE 13 AB F3TABLE 13 90 E34 51 0.6000 Infinity Glass SBSL7 516641 9.735 90 52 0.0750Infinity Air 9.710 91 E35 53 3.6122 19.2354 Glass SNPH1 808228 5.281 91E36 54 5.6250 −12.3087 Glass SLAH58 883408 4.996 91 55 3.1160 *−47.2988Air 4.142 92 56 0.0000 Infinity Air 2.995All surfaces in groups 87 and 88 are decentered along the y-axis by−4.3915 mm and +4.3915 mm, respectively, and all surfaces in groups 89and 90 are decentered along the x-axis by −3.9888 mm and +3.9888 mm,respectively. All other surfaces are aligned on the optical axis. Theasterisk (*) for surfaces 4, 7 and 53 indicate that these are asphericsurfaces.The coefficients for surface 4 are:

κ=−0.5673

A=+0.9038×10⁻⁶

B=+0.2657×10⁻⁸

C=−0.1105×10⁻¹⁰

D=+0.4301×10⁻¹³

E=−0.8236×10⁻¹⁶

F=+0.6368×10⁻¹⁹

The coefficients for surface 7 are:

κ=+0.0000

A=+0.5886×10⁻⁴

B=−0.5899×10⁻⁶

C=+0.8635×10⁻⁸

D=−0.5189×10⁻¹⁰

E=−0.1186×10⁻¹¹

F=+0.1631×10⁻¹³

The coefficients for surface 53 are:

κ=+0.0000

A=−0.5302×10⁻⁴

B=+0.8782×10⁻⁶

C=+0.7761×10⁻⁷

D=−0.1700×10⁻⁸

E=−0.1965×10⁻⁹

F=+0.6903×10⁻¹¹

The focal lengths of lens system 80 for zoom positions Z1-Z8 at focusposition F1 are 6.0003, 7.6131, 11.4304, 15.2474. 19.1105, 30.4619,41.4244, and 44.9809. The corresponding F-numbers for zoom positionsZ1-Z8 are 2.80, 2.90, 3.05, 3.25, 3.45, 3.70, 3.95 and 4.00.

For Focus Position F1 the Object Plane is assumed to be at infinity, forF2 the Object Plane is at an intermediate distance of about 1016.25 mm,and for F3 the Object Plane is at a close distance of about 378.75 mm(i.e., 378.75 mm away from the image plane). The lens groups 81, 84, 86and 91 remain in the same position throughout the full range of movementof the zoom lens group 82.

FIGS. 8A, 8B and 8C are optical diagrams of the lens system 80 showingexemplary zoom and focus positions. In FIG. 8A, the lens system 80 isconfigured for Focus Position F1 (object plane is at infinity) and ZoomPosition Z1 (F-number is 2.80). In FIG. 8B, the lens system 80 isconfigured for Focus Position F2 (object plane is at 1016.25 mm) andZoom Position Z3 (F-number is 3.05). In FIG. 8C, the lens system 80 isconfigured for Focus Position F3 (object plane is at 378.75 mm) and ZoomPosition Z8 (F-number is 4.00).

TABLE 6 provides the separation values for the last lens surface in lensgroup 81 and the first lens surface in lens group 82 for focus positionsF1-F3 and zoom positions Z1-Z8.

TABLE 6 Separation Values Between 81 and 82 Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 F10.0832 5.7132 13.7126 18.4633 21.6974 27.4007 30.5400 31.3096 F2 0.09025.7486 13.6468 18.3289 21.5154 27.0776 30.0174 30.7361 F3 0.0750 5.694213.4674 18.1217 21.3355 26.7467 29.5798 30.2701

TABLE 7 provides the separation values for the last lens surface in lensgroup 82 and the iris 83 for focus positions F1-F3 and zoom positionsZ1-Z8.

TABLE 7 Separation Values Between 82 and 83 Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 F131.5294 25.8992 17.8996 13.1486 9.9140 4.2101 1.0701 0.3000 F2 31.517825.8581 17.9590 13.2762 10.0892 4.5268 1.5870 0.8729 F3 31.5324 25.912018.1380 13.4831 10.2689 4.8577 2.0248 1.3384TABLE 8 provides the diameter of the iris for focus positions F1-F3 andzoom positions Z1-Z8 of lens system 80.

TABLE 8 Iris Diameter Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 F1 6.8689 6.5249 6.09625.6645 5.3219 4.9624 4.6915 4.6532 F2 6.8405 6.5175 6.0861 5.6557 5.29204.8816 4.5571 4.5206 F3 6.8181 6.5033 6.0661 5.6219 5.2403 4.7783 4.41324.3444

TABLES 9-13 provide the radii of curvature for liquid lens cells 85, 87,88, 89 and 90 for focus positions F1-F3 and zoom positions Z1-Z8 of lenssystem 80.

TABLE 9 Liquid Lens Cell 85 Curvature Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 F1−33.9902 −40.9700 −60.9667 −84.8892 −106.7630 −101.7297 −58.3998−48.6792 F2 −34.3890 −42.0587 −65.5384 −101.1799 −154.9184 −370.2777−263.5374 −212.3139 F3 −35.0134 −43.6001 −72.6330 −133.7178 −351.2333214.4454 125.5481 115.8049

TABLE 10 Liquid Lens Cell 87 Curvature Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 F1102.5591 118.4781 117.4984 114.8844 103.1855 99.1788 111.2567 118.9702F2 116.0979 120.8199 118.4138 110.3387 105.4622 105.8294 116.9056104.4870 F3 125.4857 126.5081 134.1777 117.6565 117.0787 126.2995145.9466 152.4400

TABLE 11 Liquid Lens Cell 88 Curvature Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 F193.9427 107.5303 107.7701 106.8706 97.5084 95.8461 104.8436 108.5809 F2102.4836 107.8382 106.2717 100.5026 97.6282 101.0075 111.6798 104.0436F3 111.5822 110.9116 94.5008 101.6873 102.7035 119.1600 146.3138155.5935

TABLE 12 Liquid Lens Cell 89 Curvature Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 F1113.3675 92.6206 99.3336 104.1798 122.1950 118.7964 88.3338 79.6583 F294.2380 92.5926 101.7948 117.8766 130.3253 125.2099 101.0682 112.6550 F385.9634 91.2575 109.5104 120.2033 127.2392 108.9338 88.7114 84.6877

TABLE 13 Liquid Lens Cell 90 Curvature Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 F192.0520 81.7616 88.9468 96.1130 117.8374 119.5041 86.4587 76.4900 F281.8570 81.1371 90.3718 106.1190 118.5283 118.2341 94.7431 108.6137 F375.0422 77.4766 87.3137 98.8610 104.4282 100.8203 87.2180 83.8997

The values provided in TABLES 9-13 are for conditions when the image isstable, and no correction for jitter is needed. When jitter is detected,the radii of curvature for the liquid lens cells are adjusted tocompensate. TABLE 14 provides the radii of curvature for liquid lenscells 85, 87, 88, 89 and 90 at Focus Positions F2 and Zoom Position Z8of lens system 80 for exemplary offsets in the x-direction of −0.5000degrees and 0.5000 degrees and in the y-direction of 0.4500 degrees and−0.4500 degrees.

TABLE 14 Liquid Lens Cell Stabilization at Zoom Position 8 and FocusPosition 2 y offset x offset (degrees) (degrees) Curvature 85 Curvature87 Curvature 88 Curvature 89 Curvature 90 +0.5000 0.0000 −212.313958.4594 −275.2157 88.1999 78.5201 −0.5000 0.0000 −212.3139 −3112.442945.3929 109.7978 121.1403 0.0000 +0.4500 −212.3139 128.0860 193.792540.6736 −1791.4629 0.0000 −0.4500 −212.3139 84.8003 101.7532 −191.663943.2782

FIGS. 9A, 9B, 9C and 9D are optical diagrams of the lens system 80configured as shown in TABLE 14. FIG. 9A illustrates image stabilizationfor an offset in the y-direction of +0.5000 degrees. FIG. 9B illustratesimage stabilization for an offset in the y-direction of −0.5000 degrees.FIG. 9C illustrates image stabilization for an offset in the x-directionof +0.4500 degrees. FIG. 9D illustrates image stabilization for anoffset in the x-direction of −0.4500 degrees.

TABLE 15 provides the radii of curvature for liquid lens cells 85, 87,88, 89 and 90 at Focus Positions F1 and Zoom Position Z4 of lens system80 for exemplary offsets in the x-direction of +1.5000 degrees and−1.5000 degrees and in the y-direction of +1.2200 degrees and −1.2200degrees.

TABLE 15 Liquid Lens Cell Stabilization at Zoom Position 4 and FocusPosition 1 y offset x offset (degrees) (degrees) Curvature 85 Curvature87 Curvature 88 Curvature 89 Curvature 90 +1.5000 0.0000 −84.889251.5591 −271.8934 143.7170 72.8023 −1.5000 0.0000 −84.8892 −762.454742.5943 103.3767 143.1168 0.0000 +1.2200 −84.8892 140.6245 113.448443.9052 −341.3372 0.0000 −1.2200 −84.8892 86.3979 81.3499 −145.466946.5625

FIGS. 10A, 10B, 10C and 10D are optical diagrams of the lens system 80configured as shown in TABLE 15. FIG. 10A illustrates imagestabilization for an offset in the y-direction of −1.5000 degrees. FIG.10B illustrates image stabilization for an offset in the y-direction of+1.5000 degrees. FIG. 10C illustrates image stabilization for an offsetin the x-direction of +1.2200 degrees. FIG. 10D illustrates imagestabilization for an offset in the x-direction of −1.2200 degrees.

The optical power and focal length ranges of the liquid lens cell datagiven in TABLES 5-15 is as follows: first cell 85 is negative topositive and −185.198 mm to +630.972 mm, second cell 87 is positive tonegative and +280.924 mm to −4154.291 mm, third cell 88 is positive tonegative and +232.078 mm to −1481.432 mm, fourth cell 89 is positive tonegative and +221.613 mm to −792.587 mm and the fifth cell 90 ispositive to negative and +235.804 mm to −1859.801 mm.

The optical performance of lens system 80 is given in FIGS. 11A-11C,12A-12D, and 13A-13D. FIGS. 11A-11C correspond to the opticalconfiguration illustrated in FIGS. 8A-8C. FIGS. 12A-12D correspond tothe optical configuration illustrated in FIGS. 9A-9D. FIGS. 13A-13Dcorrespond to the optical configuration illustrated in FIGS. 10A-10D.

The diffraction based polychromatic modulation transfer function (“MTF”)data (modulation versus spatial frequency) is shown in percent (%) forfive different Field Positions in three different combinations of thezoom and focus positions set forth in TABLE 5, namely (Z1, F1), (Z3, F2)and (Z8, F3) which are representative examples. The five Field Positions(axis and four corners) are set forth as x-y field angles in degrees.The MTF percentages are at the wavelengths and weightings set forth inthe top right-hand corner of FIGS. 11A-11C, 12A-12D and 13A-13D and aregraphically shown for x and y directions of measurement at the imageplane 92.

Lens system 80 has similar distortion characteristics as that given forlens system 60 with a slightly increased full field distortion which isslightly asymmetric due to the decentered liquid lens cells. The lenssystem 80 is substantially unvignetted and the corresponding relativeillumination is very high and similar to that given for the lens system60. The lens system 80 has a breathing characteristic substantiallysimilar to that given for the lens system 60.

The maximum spatial frequency shown is 60 cycles/mm which given theimage diameter of about 6 mm and choice of detector pixel size mayprovide high quality images at least up to approximately standarddefinition television (SDTV) resolution, namely 720 pixels horizontallyby 480 pixels vertically. At the long focal length, close focus position(Z8, F3), which is usually less important in practice than the far andintermediate distance positions, F1 and F2, the optical performance(MTF) reduces to about 55% in FIG. 11C. However, at larger distances andwith stabilization operating, the optical performance (MTF) ismaintained above about 60%. Movable lens group 82 may axially moveduring stabilization, and the variable radii of curvature of the liquidlens cells may independently change during stabilization, allowingrealization of optical performance up to or exceeding 90 cycles/mm whichis approximately equivalent to HDTV resolution.

FIGS. 12A-12D correspond to the optical configuration illustrated inFIGS. 9A-9D.

FIGS. 13A-13D correspond to the optical configuration illustrated inFIGS. 10A-10D.

The embodiment illustrated in FIGS. 7-10 utilizes a liquid lens cell 85for focus, zoom and thermal compensation; liquid lens cells 87 and 88primarily for stabilization of the incoming radiation deviated in they-direction; and liquid lens cells 89 and 90 primarily for stabilizationfor stabilization of the incoming radiation deviated in the x-direction.Movable lens group 82 primarily provides zooming. In another embodiment,liquid lens cell 85 may be removed from the system, and the remainingliquid lens cells 87, 88, 89 and 90 could provide for zooming, focusingand stabilization. Liquid lens cell 85 could also be replaced withnon-liquid lens elements. Furthermore, the movable lens group 82 may beallowed to axially move during stabilization, all of the liquid lenscell variable radii of curvature may change during stabilization orboth. This may improve the optical performance of lens system 80,especially at the corner of the field of view during stabilization.

Instead of using two pairs of liquid lens cells, the lens system 80could employ a pair of liquid lens cells to provide stabilization in asingle direction. For example, it may be desirable to reduce verticaljitter, while jitter in the horizontal direction may be bettertolerated.

The size of offset of a liquid lens cell from the optical axisdetermines, to some extent, the amount of stabilization that can beprovided by that liquid lens cell. However, the effective aperturediameter decreases as a liquid lens cell is moved away from the opticalaxis. In one embodiment, a first pair of liquid lens cells is offsetfrom the optical axis by an amount that is different from the offset fora second pair of liquid lens cells. A first pair of liquid lens cellscould provide greater stabilization in the vertical direction because ofan increased offset, while a second pair of liquid lens cells providesless stabilization but a larger aperture in the horizontal directionbecause of a decreased offset from the optical axis.

Various types of sensors may be used to detect motion of the lenssystem. For example, angular velocity sensors, piezoelectric gyrosensors, acceleration sensors, or optical detecting sensors may be usedto detect motion. U.S. Pat. No. 6,992,700, incorporated herein byreference in its entirety, discloses examples of systems for detectingmotion.

The motion sensors provide information to a controller that determinesappropriate radii of curvature for liquid lens cells 85, 87, 88, 89 and90. The controller also determines the appropriate position for lensgroup 82. U.S. Patent Application Publication 2006/0045504, incorporatedherein by reference in its entirety, discloses control of a lens system.U.S. Pat. No. 6,987,529, incorporated herein by reference in itsentirety, discloses another example for controlling a lens system.

The appropriate electronic signal levels for controlling the liquid lenscell radii can be determined in advance and placed in a lookup table.Alternatively, analog circuitry or a combination of circuitry and alookup table can generate the appropriate signal levels. In oneembodiment, a polynomial is used to determine the appropriate electronicsignal levels. Points along the polynomial could be stored in a lookuptable or the polynomial could be implemented with circuitry.

Although the figures illustrate image stabilization for a zoom lens, theimage stabilization is also applicable to any optical radiationcontrolling device, such as a fixed focus lens, a zoom lens, ananamorphic lens, an optical relay system, and the like.

Liquid lens cells may also be used in combination with other opticalelements to achieve stabilization. For example, a liquid lens cell maybe paired with a prism to improve stabilization performance. Movement oflens elements may result in a shift in image location on a sensor, atilt of the image on the sensor, or a shift in decentration. A liquidlens cell could be used to compensate for the tilt of the image on thesensor, and other lens elements could compensate for the shift indecentration or both tilt and decentration. A sensor could have extrapixels, and a motion detection algorithm, accelerometers, or gyroscopescould be used to determine the image location on the pixels and therebycompensate for image shift.

It is to be noted that various changes and modifications will becomeapparent to those skilled in the art. Such changes and modifications areto be understood as being included within the scope of the invention asdefined by the appended claims.

1. An image stabilization system, comprising: a plurality of lenselements aligned along at least two optical axes; and at least oneliquid lens cell comprising first and second contacting liquids, whereina contacting optical surface between the contacting liquids has avariable shape that is substantially symmetrical to its own optical axisand is asymmetrical to at least one other optical axis; wherein theplurality of lens elements and the at least one liquid lens cell areconfigured to collect radiation emanating from an object side space andprovide at least partial stabilization of radiation delivered to animage side space.
 2. The image stabilization system of claim 1, furthercomprising a second liquid lens cell, wherein the at least one liquidlens cell and the second liquid lens cell are configured to providesubstantial stabilization of radiation delivered to an image side space.3. The image stabilization system of claim 2, wherein the substantialstabilization is along a linear direction.
 4. The image stabilizationsystem of claim 2, wherein the radiation delivered to the image sidespace is substantially stabilized in the vertical direction.
 5. Theimage stabilization system of claim 1, comprising at least four liquidlens cells.
 6. The image stabilization system of claim 5, wherein the atleast four liquid lens cells are configured to provide substantialstabilization of radiation delivered to an image side space.
 7. Theimage stabilization system of claim 6, wherein the substantialstabilization is in a plurality of directions.
 8. The imagestabilization system of claim 6, wherein the radiation delivered to theimage side space is substantially stabilized in all directions.
 9. Animage stabilization system, comprising: a plurality of lens elementsaligned along a common optical axis; and at least one liquid lens cellcomprising first and second contacting liquids, wherein a contactingoptical surface between the contacting liquids has a variable shape thatis substantially symmetrical relative to an optical axis of the liquidlens cell; wherein the plurality of lens elements aligned along thecommon optical axis and the liquid lens cell are arranged to collectradiation emanating from an object side space and provide stabilizationof radiation delivered to an image side space.
 10. The imagestabilization system of claim 9, wherein the common optical axis of theplurality of lens elements is not aligned with the optical axis of theliquid lens cell.
 11. The image stabilization system of claim 9, whereinthe shape of the contacting optical surface is electronically controlledto provide stabilization of the radiation delivered to the image sidespace.
 12. The image stabilization system of claim 9, further comprisingan accelerometer to detect movement of at least one lens element. 13.The image stabilization system of claim 12, wherein the detectedmovement from the accelerometer is used to control the variable shape ofthe contacting liquids.
 14. The image stabilization system of claim 9,further comprising a laser gyroscope to detect movement of at least onelens element.
 15. The image stabilization system of claim 9, wherein theshape of the contacting optical surface is variable at a frequencygreater than 5 Hz.
 16. The image stabilization system of claim 9,wherein the radiation delivered to the image side space is substantiallystabilized.
 17. The image stabilization system of claim 9, furthercomprising a motion-type detection mechanism, such that panning motionis not stabilized.
 18. The image stabilization system of claim 9,wherein motion having a frequency less than 2 Hz is not stabilized 19.An image stabilization system, comprising: a first liquid lens cellcomprising contacting liquids, wherein a first contacting opticalsurface between the contacting liquids has a variable shape; and asecond liquid lens cell comprising contacting liquids, wherein a secondcontacting optical surface between the contacting liquids has a variableshape; wherein the first liquid lens cell and the second liquid lenscell are controlled in tandem to provide stabilization in at least onedirection for radiation delivered to an image side space.
 20. The imagestabilization system of claim 19, wherein a power of the first liquidlens cell is equal and opposite a power of the second liquid lens cellso that focus at an image plane is axially fixed.
 21. The imagestabilization system of claim 19, wherein a power of the first liquidlens cell and a power of the second liquid lens cell are set to providefocus at an image plane.
 22. An image stabilization system, comprising:a first pair of liquid lens cells offset from each other along anoptical axis; and a second pair of liquid lens cells offset from eachother along an optical axis, where the offset of the second pair ofliquid cells is in a direction substantially perpendicular to the offsetof the first pair of liquid cells.
 23. The image stabilization system ofclaim 22, wherein the first pair of liquid lens cells provide imagestabilization in the direction of the offset of the first pair, and thesecond pair of liquid lens cells provide image stabilization in thedirection of the offset of the second pair.
 24. The image stabilizationsystem of claim 22, wherein the first pair of liquid lens cells provideimage stabilization in a first direction, and the second pair of liquidlens cells provide image stabilization in a direction substantiallyperpendicular to the first direction.
 25. The image stabilization systemof claim 22, wherein the first pair of liquid lens cells provide imagestabilization in a first direction, and the second pair of liquid lenscells operates to allow panning in a direction substantiallyperpendicular to the first direction.
 26. The image stabilization systemof claim 22, further comprising a liquid cell substantially centeredalong the optical axis to adjust the focus of radiation delivered to animage side space.
 27. An image stabilization system, comprising: a firstpair of liquid lens cells offset from each other along an optical axis;and a second pair of liquid lens cells offset from each other along anoptical axis, where the offset of the second pair of liquid cells is ina direction substantially different from the offset of the first pair ofliquid cells.
 28. The image stabilization system of claim 27, whereinthe first pair of liquid lens cells provide image stabilization in thedirection of the offset of the first pair, and the second pair of liquidlens cells provide image stabilization in the direction of the offset ofthe second pair.
 29. An image stabilization system, comprising: a firstliquid lens cell offset from an optical axis in a first direction; asecond liquid lens cell offset from the optical axis in a seconddirection; and a third liquid lens cell substantially centered on theoptical axis, wherein the first liquid lens cell provides stabilizationalong an axis parallel to the first direction, the second liquid lenscell provides stabilization along an axis parallel to the seconddirection, and the third liquid lens cell compensates for changes in thefocus position.
 30. An image stabilization system, comprising: a firstliquid lens cell offset from an optical axis in a first direction; and asecond liquid lens cell, wherein the first liquid lens cell contributesto stabilization along an axis parallel to the first direction, and thesecond liquid lens cell contributes to focusing of radiation deliveredto an image side space.
 31. The image stabilization system of claim 30,wherein the second liquid lens cell is offset in a second directionopposite from the first direction.
 32. The image stabilization system ofclaim 30, wherein the second liquid lens cell is substantially centeredon the optical axis.
 33. The image stabilization system of claim 30,wherein the second liquid lens cell contributes to stabilization alongthe axis parallel to the first direction.
 34. The image stabilizationsystem of claim 30, wherein the first liquid lens cell contributes tofocusing of radiation delivered to an image side space.
 35. An imagestabilization system, comprising: a first pair of liquid lens cellsoffset from each other along an optical axis; and a second pair ofliquid lens cells offset from each other along an optical axis, wherethe offset of the second pair of liquid lens cells is in a directionsubstantially different from the offset of the first pair of liquid lenscells, and the magnitude of the offset of the second pair of liquid lenscells is greater than the magnitude of the offset of the first pair ofliquid lens cells.
 36. The image stabilization system of claim 35,wherein a stabilization range for the first pair of liquid lens cells isgreater than twice a stabilization range for the second pair of liquidlens cells.